Intrepid problems

Yesterday, I was congratulating myself that the upgrade I did in the morning brought Yakuake 2.9.3 back to Ubuntu Intrepid (alpha 3).
However, my jubilation was shortlived. When I shut down Ubuntu (as always had to go through Log Off and then Restart from Options) I noticed that in the login page the cursor wouldn't move and the keyboard seemed dead. However, I thought this was just a temporary problem that I could forget about.
Not so -- when I tried to boot to Intrepid this morning, both the mouse and the keyboard were totally inactive in the login screen. This effectively means you can do nothing other than a hard shutdown.
I then tried the Last Successful Boot option but this just brought me to a TTy console. Looked in /var/log/syslog but couldn't see anything obviously wrong.
I then tried an update from TTy1 (sudo apt-get update). However, nothing had changed after that -- still couldn't login.
Nothing for it but to re-install Intrepid.
Once again had to use

sudo ubiquity --no-migration-assistant

to get the install to go to completion.
In addition, I had the same problems with just a white screen showing up when I restarted the MacBook. And once again, the problem was a boot-flag causing every single one of the partitions to have a yellow warning sign (boot-flag was on first partition -- EFI). I took out the boot flag and applied. After this, all partitions became visible (no warning, data available).
However, then I put the bootflag back.
Now when I rebooted, I got the same problem again. So, back into Parted Magic and out with the bootflag.
Now I got the Apple on the rEFIt screen but no penguin.
So, I use the Hardy LiveCD to re-install the Ubuntu Grub in the MBR. I could do this while still asleep, now, but here are the steps:

1. In terminal in LiveCD, type

$ sudo grub

2. > find /boot/grub/stage1 # what partitions has Grub installed
3. > root (hd0,8) # pick the partition whose Grub you want to put in the MBR
4. > setup (hd0) # put this Grub in the MBR

You should get a seriesg of messages telling you that this has succeeded.
5. >quit # leave grub and go back to bash
and now reboot.

After all of this, Intrepid was back. After installing all 291 updates, everything worked fine, no problems.
Hard to explain why I had the problems but it's all back, at least even without an explanation.